Tibial Femoral Tunnel for Isokinetic Graft Placement Based on a Tensegrity Model of a Knee

We characterize the concept of a “knee axis” and further the concept of “invariant.” It is now generally recognized that one of the features of the tensegrity (prestressable to the same configuration) allows the knee tensegrity system to be in producing the knee instantaneous axis (KIA). We found that the line of the ground reaction force (GRF) vector is very close to the KIA. It aligns the knee joint with the GRF such that the reaction forces are torqueless. The reaction to the GRF will then be carried by the whole structures on the knee tensegrity instead. The use of knee tensegrity model introduces the new useful dimensions of sensitivity in foot loading to the knee axis alignment. We demonstrated a method to determine ideal placement of the tibial tunnel with respect to the KIA. Such placement in vivo has the potential to reliably produce an isokinetic graft without risk of impingement

AN INVERSE METHOD FOR PREDICTING THE MECHANICS OF HOPPING FROM MOTION DATA INPUT

By segmentation of the body, this study estimated both the natural frequency and mode shapes of the mechanics of hopping, during a stance phase, using a purposely developed three degree-of-freedom state space model of the leg. The model, which was validated via comparison of measured and estimated motion data, incorporated a novel use of the Bellman-Quasilinearization technique estimators. Vertical displacements of the centre of mass of each segment (thigh, shank, and foot) were collected during a stance phase and used as observed data for unknown leg compliance parameters. It was found that the relative joint contributions to compliance during an exhaustive hopping appear to be tuned in part, to the type of foot-surface landing (input signals)

The Knee Proprioception as Patient-Dependent Outcome Measures within Surgical and Non-Surgical Interventions

Proprioception considered as the obtaining of information about one’s own action does not necessarily depend on proprioceptors. At the knee joint, perceptual systems are active sets of organs designed to reach equilibrium through synergies. Many surgical procedures, such as ACL reconstruction in personalized medicine, are often based on native anatomy, which may not accurately reflect the proprioception between native musculoskeletal tissues and biomechanical artifacts. Taking an affordance-based approach to this type of “design” brings valuable new insights to bear in advancing the area of “evidence-based medicine (EBM).” EBM has become incorporated into many health care disciplines, including occupational therapy, physiotherapy, nursing, dentistry, and complementary medicine, among many others. The design process can be viewed in terms of action possibilities provided by the (biological) environment. In anterior crucial ligament (ACL) reconstruction, the design goal is to avoid ligament impingement while optimizing the placement of the tibial tunnel. Although in the current rationale for tibial tunnel placement, roof impingement is minimized to avoid a negative affordance, we show that tibial tunnel placement can rather aim to constrain the target bounds with respect to a positive affordance. We describe the steps for identifying the measurable invariants in the knee proprioception system and provide a mathematical framework for the outcome measure within the knee

Novel Computational Approaches Characterizing Knee Physiotherapy

A knee joint’s longevity depends on the proper integration of structural components in an axial alignment. If just one of the components is abnormally off-axis, the biomechanical system fails, resulting in arthritis. The complexity of various failures in the knee joint has led orthopedic surgeons to select total knee replacement as a primary treatment. In many cases, this means sacrificing much of an otherwise normal joint. Here, we review novel computational approaches to describe knee physiotherapy by introducing a new dimension of foot loading to the knee axis alignment producing an improved functional status of the patient. New physiotherapeutic applications are then possible by aligning foot loading with the functional axis of the knee joint during the treatment of patients with osteoarthritis

An Inverse Method for Predicting Tissue-Level Mechanics from Cellular Mechanical Input

Extracellular matrix (ECM) provides a dynamic three-dimensional structure which translates mechanical stimuli to cells. This local mechanical stimulation may direct biological function including tissue development. Theories describing the role of mechanical regulators hypothesize the cellular response to variations in the external mechanical forces on the ECM. The exact ECM mechanical stimulation required to generate a specific pattern of localized cellular displacement is still unknown. The cell to tissue inverse problem offers an alternative approach to clarify this relationship. Developed for structural dynamics, the inverse dynamics problem translates measurements of local state variables (at the cell level) into an unknown or desired forcing function (at the tissue or ECM level). This paper describes the use of eigenvalues (resonant frequencies), eigenvectors (mode shapes), and dynamic programming to reduce the mathematical order of a simplified cell–tissue system and estimate the ECM mechanical stimulation required for a specified cellular mechanical environment. Finite element and inverse numerical analyses were performed on a simple two-dimensional model to ascertain the effects of weighting parameters and a reduction of analytical modes leading toward a solution. Simulation results indicate that the reduced number of mechanical modes (from 30 to 14 to 7) can adequately reproduce an unknown force time history on an ECM boundary. A representative comparison between cell to tissue (inverse) and tissue to cell (boundary value) modeling illustrates the multiscale applicability of the inverse model

ANALYSIS OF LEFT ARM SEGMENTAL CONTRIBUTION IN GOLF SWING

The object of this study is to examine the segmental movement of the left arm in a golf swing and determine its contribution to the final club head speed. In order to examine this movement, a procedure for quantifying joint movement was developed. Electrogoniometers (Biometrics, UK) with frequency of 1000 Hz were attached to the subjects during the execution of the swing to obtain the joint angles throughout the motion. The velocities of the segment rotation can be computed with dual velocity analysis. A zero handicapper was tested with the method. The method uncovers the importance of longitudinal segmental rotations in his swing. These rotations are often neglected in 2-dimensional approaches

Validation of a Biomechanical Injury and Disease Assessment Platform Applying an Inertial-Based Biosensor and Axis Vector Computation

Inertial kinetics and kinematics have substantial influences on human biomechanical function. A new algorithm for Inertial Measurement Unit (IMU)-based motion tracking is presented in this work. The primary aims of this paper are to combine recent developments in improved biosensor technology with mainstream motion-tracking hardware to measure the overall performance of human movement based on joint axis-angle representations of limb rotation. This work describes an alternative approach to representing three-dimensional rotations using a normalized vector around which an identified joint angle defines the overall rotation, rather than a traditional Euler angle approach. Furthermore, IMUs allow for the direct measurement of joint angular velocities, offering the opportunity to increase the accuracy of instantaneous axis of rotation estimations. Although the axis-angle representation requires vector quotient algebra (quaternions) to define rotation, this approach may be preferred for many graphics, vision, and virtual reality software applications. The analytical method was validated with laboratory data gathered from an infant dummy leg’s flexion and extension knee movements and applied to a living subject’s upper limb movement. The results showed that the novel approach could reasonably handle a simple case and provide a detailed analysis of axis-angle migration. The described algorithm could play a notable role in the biomechanical analysis of human joints and offers a harbinger of IMU-based biosensors that may detect pathological patterns of joint disease and injury

An Informational Algorithm as the Basis for Perception-Action Control of the Instantaneous Axes of the Knee

Traditional locomotion studies emphasize an optimization of the desired movement trajectories while ignoring sensory feedback. We propose an information based theory that locomotion is neither triggered nor commanded but controlled. The basis for this control is the information derived from perceiving oneself in the world. Control therefore lies in the human-environment system. In order to test this hypothesis, we derived a mathematical foundation characterizing the energy that is required to perform a rotational twist, with small amplitude, of the instantaneous axes of the knee (IAK). We have found that the joint’s perception of the ground reaction force may be replaced by the co-perception of muscle activation with appropriate intensities. This approach generated an accurate comparison with known joint forces and appears appropriate in so far as predicting the effect on the knee when it is free to twist about the IAK